Lately my Scrambler has been hard to start and in general slower that what I remember. Took it to the dealership the she pumped out only 60 cylinder psi, anything under 90 is junk! I was amazed that it would even run at all.

I removed the cylinder and piston, no damage just wear. Had the cylinder bored .040 and a new Wiseco piston. Put it together, everything went fine. I mixed 40:1 pre-mix in the tank as well as what the oil injector will put out.

Well, it starts right up but when you drive it around it bogs down and dies every time. Almost like it isn't getting any gas, but it is. It will idle all day long until you drive it for about one minute and then it dies. Funny thing is, it will start right back up again. It FEELS like the piston is locking up, but then why does it re-start?

I am out of ideas and I had a big riding trip planned for the weekend. Looks might I might be staying home. Please help if you can. Thanks.

'96 Scrambler 400
HPD Trail Pipe/FMF Turbine Core II
HPD Agg. clutch kit
Carbon Tech reeds
K&N filter
HSP billet head
Wiseco piston

......but will not run!

 

Couple of things to check:
1)Fuel filter:LH side of tank by oil injection filter.
2)Retorque cylinder:After the first good warmup, you should always retorque the base of the cylinder...that's a trick from HPD.
3)Check the jetting/sparkplug. Are you using the BR8 or BR9. Sometimes these are a bit finicky (sp?)especially if you're "leaning" things out with the additional premix. That extra oil is in fact displacing extra fuel.
4)Double check your intake boot. I would imagine you checked the condition of your reeds when things were torn down.


Sometimes the most frustrating things can be cured by the simplest things.

Ken

 

Could I have an air leak somehwere? With all the oil shes burning, I hope I did not do any damage to it already?

Reeds are new, they went in with the new piston. Mt spark plug is burning very clean, maybe even alittle bit lean. I am going to check my fuel filter as well. Hope I can figure this one out. Thanks.

 

Sounds like an intake leak to me.Check your boots for cracks and be sure they are tight.The older 400s had faulty intake boots(the one from the air box to the carb)but check both.

 

Here is another shot in the wind. Check your gas tank vent hose and make sure it's not kinked off. It could be allowing enough air to idle and run for a bit, but cutting enough air off to not run all the time. Just giving you some ideas, but this hose being kinked has happened to me before right after I reassembled mine.

Also one time instead of putting the hose up by the steering stem like it's should be, I let it hang back one time, and it somehow went into the intake hole on my air box. And it did exactly what you described because it was causing a vacuum and sucking all the air out of the tank, not allowing gas to get to the carb. But after it stalled, and air reentered the tank it would fire back up for a bit. Hope this helps.

Also you don't need to run that extra oil in your motor during break-in. It actually can lube the piston to much making break in last a lot longer. I just stick 32:1 in all motors I work on, and let em go. Oh and if it makes you feel better I've only had 30lbs. of compression before, and my motor somehow still ran. It didn't run worth crap, plus it sounded like a sick banshee, but it ran. Although it took 5 minutes of cranking to get it to fire up. I have a witness on the boards here that can tell you it ran to. Where's walexa when you need him??

 

There's some more, good luck. Keep us posted please.

Ken

 

mine was doing the SAME thing,NEEDLES JETTING TOO RICH,lean it out.

 

I can see the fuel tank vent line getting pinched thing happening. Kinda in a bad spot when you put the front fenders on. I will take a look at it this weekend. Good ideas guys. Adam

 

Before taking the tank off put about a gallon of fuel in the tank and start it. Let it warm up then just sitting outside see what it will throttle up to. If it will throttle up pretty high and not have any problems that should tell you if the vent is stopped up. I had a stopped up vent and a old mechanic told me to do this first. Be sure it is good and warm and not in gear.

Ronnie

I forgot to tell you but you have to leave the gas cap off.

 

I checked and double checked everything that you guys suggested and still does the same thing. Even thought it was the CDI box but wasn't.

I did get it to run for about 1 hour the other day before she died. This time it would turn over but not fire. Shoot..thought I had her going.

Anyway....I am stumped and it's going to the dealership. Maybe we are looking at a bad piston/bore job relationship here. If so, I wont have them bore my cylinder again. Rick Ritter will get some business via trail ported cylinder and we will start over again.

Thanks anyway guys! I will keep you posted on what we find.